Debugging culling in InstancedMesh and Orthographic camera

I am trying to make a simple InstancedMesh demo using cubes in an isometric perspective scene (with Orthographic Camera). I want to disable culling of meshes. Things I have tried:

  1. Setting frustumCulled = false
  2. Near plane = 0
  3. Far plane to a high number
  4. Enabling the CameraHelper to see the frustum

Glitch link

What am I missing? Why do the cubes still get culled when viewing at an angle?